Well after years of being on the sidelines I decided to voice my concerns for the high end industry. Since my teenaged years I have loved the listening to good music through good equipment. I became an Electrical and Mechanical engineer, which was due in part to my love for building my own DIY equipment at home.

After reading Stereophile’s review of the Simaudio’s Moon Evolution 800M, I just couldn’t stand on the sidelines and not voice a concern about specmanship in the highend audio industry. I thought the large differences in published specifications vs. actual measurements was relegated to consumer electronics and not to five and even six figure (hopefully) state of the art audio equipment. The Evolution 880 clearly does not achieve some of the most important specifications that amplifiers are measured to.

The output power specification for this amplifier is continuous for only an 8 ohm load. The 4 ohm specification of 1600W is clearly momentary, or “peak” as the 10A fuse limits the output power to 1050W.

The argument that using a continuous sine wave to test amplifiers is not fair to the amplifier is incorrect. Wattage is Wattage, whether it’s from a music source or a function generator. A music source is said to have dynamics and therefore not tax the amplifier as a continuous sine wave does. This is true, but to do away with the ambiguity of testing amplifiers, the Industry uses the term as “rated continuous output power”. If an amplifier is rated to output 800W most manufactures that follow IEC specification would specify it for continuous output power. This should be done with a sine wave a 1khz, but even if it’s done with a music source, the average power must equal a continuous 800W. Of course to output 800W of continuous RMS music power would require clipping the signal or having the music highly compressed. Power is Power. Can the Evolution output 1600W of continuous music power into 4 ohms? No.

TEMPERATURE

The other very alarming measurement of the Evolution 800M is that a 1/3 power into 8 ohms the heat sinks reach dangerous temperatures. Other that than the high end amplifier industry, most manufactures limited exposed surface temperatures to 50C or less. The high end industry seems to be fine with much higher temperatures. The Evolution 800M has surface temperatures of 73.5C. The SAFETY standard UL/ IEC 60950-1 for electronics allows for metal surfaces to reach 70C.

As with all of Simaudio's amplifier, the heat sinks are mounted with the fins in a horizontal plane rather than the traditional vertical plane. I assume they chose this for looks rather than cooling efficiency, since this arrangement is a very poor utilization of natural convection cooling. The purpose of using a heat sink with vertically mounted fins is to take advantage of the rising natural convection air moving over as large of a surface area as possible, with little or no obstruction in its motion.

CONCLUSION

I wish Stereophile would include in their review language that clearly states that the product does not meet its specification in the final summary of the measurements section of the articles. Instead in this article a poor excuse is given for it not being able to drive low impedance loads, but the review said that’s OK because music is not a sign wave. For heaven sake, this is a $42,000 amplifier and should perform as specified as do many "afordable" Best Buy purchased equipment.

I am very happy that Sterophile does actually test the equipment they listen to. Most other reviewers do not. It is a great service to all of us. The whole purpose of the review is to provide both objective and subject information to the reader so that they may know what they will be getting when they purchase the item.

I understand that the subjective portion of the review can have no objective scales, but when objective measurements are made they are very much tied to real physical scales set forth by various international agencies. My only other concern is that I have found in the last few sentences of the measurement section, a subjective assessment made of the objective measurements that not only seems to trouble others ( as I have read in posts on stereophile.com) but myself as well. There have been recent reviews of amplifiers that for their astronomical price have very poor measurements. At the end of the review a subject remark is made like “This is an amplifier that is as well-engineered as it is beautiful to look at.” That may be the reviewer’s opinion, but as an Electrical Engineer of 20 years’ experience and who closely follows both DIY and professional audio design, I had a very different opinion and hold the standards for saying “This is an amplifier that is as well-engineered “for such high priced equipment to a higher level. I would never have said what the review said for that product.

I am trying to be constructive with my comments and mean no disrespect to any of the reviewers.

1) My measurements of output impedance include the series resistance of 6 feet of approximately 14-gauge speaker cable.

2) Yes, the fuse blew under sustained drive into 4 ohms. But it is entirely possible that with a pulsed signal with a low duty cycle, the fuse would remain intact up to the clipping point. Note, BTW, that I don't hold the wall voltage constant for these tests, feeling that this is more representative of actual use.

2) Most energy will come from low-frequency musical elements and those are everything but low duty pulses. Most of them will be closer to sine waves and they will suck a lot of power when driven into speaker loads so there is still a risk to blow the fuse on bass-heavy music played loud.

You have been warned multiple times, Johnny R, that posts of yours that in our opinion are nothing more than abuse or trolls will be deleted without notice. You don't want your posts deleted, please refrain from personal attacks and stick to addressing the points being made by others.

JohnnyR wrote:

This amp FAILS at a number of tests and should have been criticised for doing so NOT praised.

Please think about where you learned about this amplifier's apparent shortfalls in its measured performance.

just change the specs to be a bit below where actual problems arose then jack up the price even more and they would have a "winner" I understand it could double as heater during the cold months. This brings about the possibility of owning another amp that doesn't get hot for the summer months. A win-win for the high end dealers that wish to double their profits.

From the company's website: "The Standard Warranty is 1 year parts and labour.

"Upon receipt of a validated Product Registration (via our website or by regular mail), the warranty can be extended up to an additional 9 years.

"To receive this free-of-charge extended warranty (up to 10 years), the product must have been purchased new, from a MOON Authorized Dealer. and registered with us within 30 days of your invoice date."

If you read Stereophile's review of the Bryston 28B-SSTyou will find that it was another very “hot” amplifier.

From Stereophile review:

“I preconditioned the Bryston 28B-SST by running it at 330W into 8 ohms for an hour. ….. The amplifier's heatsinks were way too hot to touch after 60 minutes, but despite the thermal abuse, the amplifier didn't turn itself off.”

What is way too hot to touch? This can be quite subjective, but is usually considered starting between 65-70C. That is when contact for more than a brief few seconds leads to a burn. The Bryston 28B-SST temperature was clearly above this threshold based on Stereophile’s test.

I would not consider the Bryston 28B-SST to be designed thermally any better than the Evolution 800M. That being said, the Bryston 28B-SST functioned through the entire tests without failure.

I agree that with higher temperature two things must be considered by a buyer. First is the placement of the equipment where it will get enough ventilation as well as not being touched when driven hard. The second consideration is that the MTBF (Mean Time before Failure) increases with higher operating temperature. Temperatures of 70C are not destructive to most electronic components since most are rated much higher. The component that is most affected by high temperatures are electrolytic capacitors the bulk of which are the main power supply filter/storage capacitors. The life time of these are impacted quite drastically as temperatures go up.

You would defiantly want a robust warranty on a “hot” running amplifier.

I appreciate the difficulty that designers of amplifiers face. There are many unknowns to the designer. The most unknown is the load. Some speakers are easy to drive, some are very difficult. Speakers are complex loads and can drop their impedance to half or less of their rated impedance at certain frequencies. Not only that, but during these low excursions the current and voltage can be way out of phase and that puts the highest stress on the amplifier’s output transistors.

I believe that over the many decades that this industry has been around; the adoption of standardized testing methods and specifications has helped to alleviate the ambiguity of how a particular amplifier can perform. Tests like the 1/3 power test into load, the specification of continuous RMS power into 8,4 or 2 ohms loads, etc., give the buyer the tools with which to marry a speaker with an amplifier. Of course the tests do not reflect “real life” music listening, but they are not meant to. They are meant to give assurance that they can at least play music continuously at a rated power in to a rated load.

Do we listen to music at continuous RMS value of let say 800W. Most likely not. But then, what music are you listening to. Is it highly compressed? Does it have a lot of low frequency component which where most of energy goes in recreating music. What speaker are you driving?

What is way too hot to touch? This can be quite subjective, but is usually considered starting between 65-70C. That is when contact for more than a brief few seconds leads to a burn. The Bryston 28B-SST temperature was clearly above this threshold based on Stereophile’s test.

The Bryston was reviewed before I bought an infra-red thermometer. But I was taught at university that "too hot to touch" or more accurately, to keep your hand on" was equivalent to >60C.

And the one hour at 1/3 power test is very much a worst case for amplifiers with a class-B or -AB output stage like the Bryston and Simaudio.

Sorry but , "I think this amp sounds better" with no objective testing is guess work and just opinion. Amps need to meet their specs otherwise the manufacturer is making a faulty product. If they can't meet their own specs then how can you trust it to last or perform at it's best?